Paint gun



T. BIRKENMAIER y PAINT GUN Filed 06t- 18. i924 lult 39. L?? l li if i Y* iatentefd heb. 26, 1929.

Unirse `STATES PATENTfoFFIcs.-

THEODORE BIRKENMAIFR, OF ST. LOUIS, MISSOURI, ASSIGNOR TO W. N. MATTHEWS CORPORATION, OF ST. LOUIS, MISSOURI, A CORPORATION OF MISSOURI.

PAINT GUN.

Application med october 1s, 1924. serial No. 744,334.

This invention relates to coating apparatus, and lwith regard to certain more specific features, to spray guns for applying liquids as a coating to surfaces.

Among the several obj ects ofthe invention may be noted the provision of apparatus for sprayingliquids such as paints, varnishes and the like, and more especially quick drying kinds of these liquids; and the provision of means for preventingthe formation of air bubbles in the coating material as it is sprayed. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the features of construction, combinations of ele,-

ments and arrangements of parts, which are exemplified in the .description hereinafter in connection with the accompanying drawings, and the scope of the applicationv of which will be indicated in the following i claims.

In the accompanying drawings, inwhich is illustrated one of various possible embodiments of the invention,

. Fig. 1. is a side elevation of the spray gun assembled with parts broken away;

Fig. 2 is a front view of the nozzle; and

Fig. 3 is an enlargedl longitudinal section of the nozzle tip and nipple showing the nozzle casing adjustedforwardly.

Referring now more particularly to Fig. 1 of the accompanying drawings there isil- -lustrated at 1 a body for the gun. This body is provided longitudinally kwith a paint or material passage 3 and a compressed air passage 5. Each passage is enlarged at its rearward opening to receive a valve mechanism.

At the rear of the body 1, and screwed substantially upwardly therein, are two supply pipes, 7 and 9, one for air and one for spraying material under pressure. The material pipe 7 is located forwardly of the air pipe 9 and is adapted to be capped witha dead-end nipple 11, the use of which will appear later. These pipes 7 and 9 are enclosed by a grip 13 which is held up against the body 1 by nuts 15 and 17. An air supply line 19 of flexible material is coupled to the air pipe 9 by means of the nipple 21. A guard 23 extendingrearwardly from above the grip and on the body prevents the head from slipping upwardly from said grip. V y

kwardly at (see Fig 1).

The -material supply pipe 7 communicates with the material passage 3 by means of the bpre 25 which is offset vertically to pass the air passage 5 untouched, and is Yclosed at its upper end by the plug 27.L The air supply pipe 9v communicates with the air passage 5 by means of the bore 29. vThe described ar-k rangement vfor the passages lends` itselfto easy manufacture. l

VIn the present embodiment liquid under pressure maybe supplied to the passage 3 through the pipe 7 by ,uncoupling the deadend nipple 11 and fastening a flexible liquid supplyline similar to the flexible air line 19.

However,l inasmuch as quick-drying liquidsl are seldom mixed in. large enough batches to warrant the use of an independent reservoir, it is intended to provided a small reservoir on the spraying apparatus itself.

An upwardly extendinglug3l is provided on the body 1, and is bored at 33 to meet the material passage 3. To this lug is threaded the reservoir cup 35. This cup 35 supplies liquid tothe material passage 3. It is providedl with a cover 37 which may be clamped down on the cup 35 by means of cooperation between the wedges 39 on the downwardly extending ears 41 of the cover 37 vand the slanting lugs 43 of the cup 35. It is clear that this cooperation may be brought about by first placing the cover 37 on the cup 35 and .then twisting saidcover to the left. A sealy ing gasket 45 placed in a groove in the cover becomes interposed between said cover and the cup, thus preventinga liquid therein from drying.

The material and' air passages Band-5, re-i. spectively, end forwardly in a nozzle cylinder 47 formedvat the forward end of the gun (Fig. 1). The material passage 3 is threaded at its forward end within this cylinder 47 and receives the nipple 49 which nipple contains the passage 51 as a continuation of the paint passage 3. ',The details of this nipple will be described later.

n Around the nozzle cylinder 47 is placed the snugly fitted nozzle casing 53 flanged out- This flange abuts the threaded ring 57 over which ring r57is forced with a press fit,*the flanged outside ring 59. A flange 61 on. ring 59 cooperates with flange 55permitting the latter to turn freely with respect to the rings 57 and 59,

which rings are `one piece to all intents and purposes. The ring 57 is provided with an outwardly extending stopelange 03 for stopping the lpressing on of ring 59 'when the proper tolerance for easy rotation of flange has been obtained. lVhen the threaded ring 57 is screwed to the nozzle cylinder its rotation in screwing iton, causes a longitudinal movement of the nozzle casing 53 on the nozzle cylinder 47 without necessarily causing said casing to rotate.' Rotation of the nozzle casing on the nozzle cylinder is, however. free to be accomplished by other means.

The forward end of the nozzle cylinder or casing tapers inwardly lorn'iing the air chamber which receives its air supply from the passage 5. As will be described later, some pressure will build up in this chamber 65 so that a seal is needed between the casing and cylinder. This is acconr'ilished by cutting a groove at the end of the cylinder and placing a soft gasket 67 therein. Against this gasket is placed a forwardly (lished metallic washer 69 having a ei-ntral hole therein adapted to receive the nipple 49. A shoulder 71 on the nipple tends to iatten ont the dish shape of the washer as the nipple is screwed home in the end of the paint passage, thereby forcing the edges of the washer to exert a local pressure on the gasket 07 and causing it to seal the joint between 'the casing and cylinder. The washer has a hole 73 cut therein to permit air to pass from the passage 5 to the chamber 65.

As beforel described, the forward end of the casing 53 tapers imvardly to a nozzle tip 75. This tip 75 comprises a centrally bored plug which is forced into the forward end of the casing. Said central bore is adapted to receive snugly, a projecting cylinder 77 of the nipple l-9. The tip 75 is also provided with air discharge ducts, 79 and 81, which end forwardly in such a fashion as to direct air forwardly and convergingly toward the center of the nozzle. These ducts are arranged preferably at 180 degree intervals, there being two of them.

As indicated the projecting cylinder' 77 of the nipple 49 entends slidably into the tip 7 5. This cylinder 77 is provided with a it'orwardly projecting cylindri :al teat 83 bored to meetthe passage 51 and provided with a cleaning plugv85 in the bore. This plug i5 is integrally formed with the valve plug S7 on the material valve stem 89. This stem 89 and the two plugs 87 and S5 are capable of being withdrawn rearwardly to the dotted line position shown in Fig. 3, thus opening the material passage of the nozzle. A guide spider 91 holds the assembly within the nipple in alignment.

The material valve stem 89 and stem 93 of the air valve have adjustable nuts 5 and 97 mounted rearwardly thereon. The nuts engage saddle straps 98 and 100, reaching around the gun and pivoted to the trigger 99V which is itself pivoted to the body 1 at 101. llhen the trigger 99 is pressed the valve stems are caused to be drawn rearwardly. This is brought about by means of the engagement between 'the saddle portions 103 and 105 of the straps and enlarged lrnurled portions ofthe nuts 95, 97. However the saddle portion 103 of the material valve strap rides on a cylindrical portion 107 of the nut before striking the enlarged portion mentioned thus permitting the air valve to be opened lirst and obviating the possibility of spreading any unatomized paint when starting the apparatus.

The operation of the device' isas follows:

The nozzle may be adjusted asshown in F ig. 1, i. e., with air ducts 79 and 81 impinging on the teat 8 3 and vertically positioned with respect to one another. The cup 35 is filled with liquid. Upon pressing the trigger, the air valve is immediately opened, inasmuch as the saddle portion 105 was already in contact with the enlarged portion of nut 97. Air then flows from the flexible conduit 19, through pipe 9, the air valve, duct 5, through chamber 65, and out of the ducts 79, 81, to be impinged on the teat 83. n Incidentally, as it leaves the ducts it exerts an aspirating effect.

As the trigger is further pressed the saddle 103 rides over the cylinder 107 and contacts with the enlarged portion of nut 95 thereby opening the material valve. The material under a head or pressure finds its way out of the teat 83 and is picked up by the. aspirating air, atomized and thrown on the surface to lbe covered. lnasmuch ras only two ducts such as 79 and 81, beside the symmetrical central ejection from between cylinder 77 y and plug 75 are present, theair exerts a. distorting effecton the'issuing circular section of paint causing it to take a desirable elliptical or ovate shape. The tcat 83 counteracts this effect somewhat. Tf the full effect of flattenin the spray is wished for, without counteraction, it is only necessary to force the casing forwardly to a position such as shown in Fig. 3, whereupon the teat becomes inef-Y fective and the spray becomes great-ly eccentric instead of only slightly so.

lf desired the ducts 79 and S1 may be adjusted to a horizontal relationship thus giving a vertically elliptical spray instead ofthe horizontally elliptical one to be expected here.

lt should be noted here that the air ducts are close te the point of paint ejection and the expanding air from the ducts therefor forms small vacuum pockets rearwardly of said ejecting air. The pressure on the paint before ejection is, by gravity or otherwise, made just enough to overcome line friction and thus bringit to the nozzle independently or any aspirating action. At this point, the

paint is drawn outwardly and iningles with. the jet of air which draws it. In previous types of sprayers, the air jets form no vacuum pockets but merely play on a pressure ejected stream of paint. 'Ihis-resnlts in a rolling np and swirling ofthe paint .stream as it strikes the impinging air stream with the result that air bubbles are engendered. These are detrimental to surfacesl which should Vhave smooth coatings.`

From the above it will be seentliat the several objects of the invention are attained and other advantageous results achieved.

As many modificati ons the embodiment-s above illustrated might be made without departing from the spirit of scope of the present invention, it isintended that the above description and accompanying dra rvings and claims shall be interpreted as illustrative and not in a limiting sense.

I claim:

l. In a nozzle Jr'or coating apparatus the combination of a nozzle cylinder, a nozzle easing adjnstably mounted thereon tor longitudinal n'iovenient, a nipple lastened to said cylinder having a cylindrical. portion, a nozzle tip in said casing independent of said cylinder adapted to slidably engage said cylindrical portion of the nipple, and ducts in said tip. l

2. In a nozzle for coating apparatus the combination of a nozzle cylinder, a nozzle casing adjustably mounted thereon for longi tudinal movement, a nipple fastened to said cylinder, a nozzle tip in said casing indepen dent of said cylinder adapted to slidably lit said nipple at a cylindrical portion and diictsV in said tip adapted to draw material from said nipple when ,air is ejected i'trom the ducts.

3. In a nozzle 'for coating apparatus the combination ot a nozzle cylinder, a nozzle casing adjustably mounted thereon for lon gitiidinal movement, a nipple fastened to said cylinder, a nozzle tip in said casing independent of said cylinder adapted to slidably fit said nipple at a cylindrical portion and ducts in said tip independent of said nipple adapted to draw material from said nipple when air is ejected from the diicts. l

a. In a spray gun the combination of, a body, a reservoir mounted. on and above said body, a nipple in communi ation with said reservoir, a nozzle tip sliiflably cooperating `with said ni )ole at a cylindrical Dertien and.k

ducts in said tip adapted to eject an aspirating stream oli air ahead of said nipple, a com# pressed air passage in said body communicating with said ducts, a teat on saidnipple adapted in one position of said nozzle tip to be struck by said stream of air and in another position of said nozzle adapted not tobe struck by said stream of air.

5. In a spray gun the combination of, a body, a reservoir mounted on and above said said nipple` andfducts in 'said'tip adapted toy eject an aspirating and di'storting streamot air ahead of' said nipple, and a teat on-said nipple adapted to counteract the distorting eil'ect of the air stream when said nozzle 'tip is ina retracted position.

6. In a spray gun the combination of, a body, a reservoir Amounted on and above said body, a nipple in communication with said reservoir, a valve in said nipple, a teat on said nipple and a cleaning plug in said teat integral with said valve, a nozzle tip slidably cooperating with said nipple adapted to cooperate' with said nipple,-ducts in said tip'adapted to eject an aspirating and distorting stream of air ahead of said nipple and upon or ahead of said teat according to` adjustment. Y

7. In a spray nozzle the combination ol a cylindeiga casing over said cylinder, a tip on said easing .means for sealing the joint be-v tween said cylinder `and casing, an ejecting nipple adapted to make the sealing means 9. In a spray nozzle the combination o'ta cylinder, a casing over said cylinder, a tip on said casing means for sealing the joint between said cylinder an'd casing, an ejecting nipple adapted to making the sealing means operable and cooperating slidably with said tip and a projecting teat on said nipple adaptedto extend forward of said tip.

l0. In a spray nozzle the combination ot' a cylinder, a casing over said cylinder, a tip on said cylinder, passages in said tip ada ated to eject air forwardly and angularly toward a common center thereby creating a low pressure area rearwardly, means for sealing the joint between said cylinder and casing, a delivery nipple adapted to making the sealoperable and cooperating slidably with .said

llO

ing n'ieans operable, cooperating slidably with said tip and an: )ted to deliver material into the said low pr .ssure area.

ll. In a. spray nozzle the .combination ot a cylinder, a casing over said cylinder, a. tip

on said cylinder, passages in said'tip adapted vto eject air 'forwardly and angularly toward a common center thereby creating f a low pressure area rearwardly, means 'for sealing the joint between said cylinder and casing, a delivery nipple adapted to making the sealing means operable, cooperating slidably with said tip and adapted to .deliver material into the low pressure area, and e reet on said nipple 'adapted to come into the pduh of vsaid ejected air.

1Q. In a spray gurl thel combination or" a nozzle cylinder, a nozzle casing adjueably mounted thereon for longitudina movement, a` material outlet nipple on said eyinder and :L Separate nozzle tip formed in said casing and cooperating with the. nipple, said tip being adapted to eject air.

In testimony whereof, l have signed my name to this specificalion this 16th @Ciohera 1924.

THEGDRE BIRKENMAER.

day of 

